Umarex [VIDEO] Glock 17 gen 5 mos : upgrade for more power !

[Clark33]

This Umarex Glock 17 features a 21 shot chain magazine and delivers 350 fps with 0.45 g pellets out of the box, which equals 2.56 joules.
This is low, but still within the standard range for a .177 blowback pistol. Its stock performance is below the PPQ M2 Q4 from the same series
that also use a chain magazine, which I own and which reaches 400 fps on the first shot : between 3 and 3.2 joules. So I decided to completely rework the magazine, the valve, and its spring for maximum performance. These modifications increase power by over 2 joules while also improving shot consistency, despite the usual limitations of blowback systems.


The magazine head was fully machined to increase CO₂ volume, with a significant amount of metal removed. The small stock valve had
two very narrow inlet holes and an internal outlet diameter of 2.90 mm. I reamed it to 3.40 mm and greatly enlarged the CO₂ inlets.
A softer and more suitable spring was installed. I now get extremely consistent velocities for a blowback pistol, with a peak of 4.58 joules.
Even higher power is possible with slightly heavier pellets, but the result is already very satisfying.
This is probably one of the most powerful CO₂ blowback pistols in .177 today.


I also mirror polished the plate that presses the chain against the magazine to reduce friction during rotation and improve trigger feel.
I built a quick-piercing system by machining a piece of Allen key and a butterfly knob in carbon fiber, which turned out too fragile.
I then remade it in aluminum and applied a Cerakote finish. This eliminates the need for a tool to pierce the CO₂ cartridge.

Chrony test : https://streamable.com/2wq04g​

75.2 °F, 0.45 g pellets
​

(FPS) (Joules)

455.5 4.33
459.2 4.41
462.1 4.45
468.0 4.57
464.4 4.50
450.3 4.24
452.3 4.28
448.7 4.21
438.2 4.01
432.3 3.90



Max : 4.57j
Average : 4.3j

 

[Clark33]

Next step: long barrel ! The original is 11 cm (about 4.3 inches), and considering the CO₂ cloud it releases after the modifications, I'm sure it can benefit from a longer one. The new barrel is a 15 cm, taken from a 6-inch barrel of the Crosman Triple Threat. As long as it’s not too long, it should help. The blowback system sends part of the CO₂ backward, and if the barrel is too long, a suction effect can occur inside, which would have the opposite effect and slow the pellet down.

 

[borne2fly]

This Umarex Glock 17 features a 21 shot chain magazine and delivers 350 fps with 0.45 g pellets out of the box, which equals 2.56 joules.
This is low, but still within the standard range for a .177 blowback pistol. Its stock performance is below that of the PPQ M2 Q4 from the same series,
also with a chain magazine, which I own and which reaches 400 fps on the first shot, between 3 and 3.2 joules.


I decided to completely rework the magazine, the valve, and its spring for maximum performance. These modifications increase power by over 2 joules
while also improving shot consistency, despite the usual limitations of blowback systems. The magazine head was fully machined to increase CO₂ volume,
with a significant amount of metal removed. The small stock valve had two very narrow inlet holes and an internal outlet diameter of 2.90 mm.
I reamed it to 3.40 mm and greatly enlarged the CO₂ inlets. A softer and more suitable spring was installed. I now get extremely consistent velocities for
a blowback pistol, with a peak of 4.58 joules. Even higher power is possible with slightly heavier pellets, but the result is already very satisfying.
This is probably one of the most powerful CO₂ blowback pistols in .177 caliber today.


I also mirror polished the plate that presses the chain against the magazine to reduce friction during rotation and improve trigger feel.
I built a quick-piercing system by machining a piece of Allen key and a butterfly knob in carbon fiber, which turned out too fragile.
I then remade it in aluminum and applied a Cerakote finish. This eliminates the need for a tool to pierce the CO₂ cartridge.

Chrony test : https://streamable.com/2wq04g​

75.2 °F, 0.45 g pellets​

FPS | Joules

455.5 | 4.33
459.2 | 4.41
462.1 | 4.45
468.0 | 4.57
464.4 | 4.50
450.3 | 4.24
452.3 | 4.28
448.7 | 4.21
438.2 | 4.01
432.3 | 3.90

Max : 4.57j
Average : 4.3j

Good stuff! I was wondering how to improve all that!
You’re an evil man, Clark …. you’ve armed me with the info I need to start yet another project .

 

[Clark33]

Machining complete !

I ended up installing it on the umarex PPQ M2 Q4 tac combo, since it's equipped with a suppressor that can hide the extra 4cm/1.6 inches of barrel.
Even though it has similar mods on the magazine and valve, and slightly higher out of the box power, the results are a bit lower on the PPQ after
tuning : max 450 fps, compared to 468 fps with the Glock. But more importantly, consistency is worse : the power drops off more quickly.
Still, performance is much better than stock !



Test of the PPQ M4 with the same mag mods, stock barrel, and 0.45g pellets.

Chrony test : https://streamable.com/ed0rb7​

First test with the "long" barrel, 0.45 g pellet : nearly 500 fps ! (CO2 already slightly used)
5.08 joules, a gain of almost 50 fps, so it's working.

Chrony test : https://streamable.com/x6t3g3​

Second test with 0.51 g pellets : 464 fps, 5.10 joules

Chrony test : https://streamable.com/xulycu​

 

[borne2fly]

Machining complete !

I ended up installing it on the umarex PPQ M2 Q4, since it's equipped with a suppressor that can hide the extra 4cm/1.6 inches of barrel.
Even though it has similar mods on the magazine and valve, and slightly higher out of the box power, the results are a bit lower on the PPQ after
tuning : max 450 fps, compared to 468 fps with the Glock. But more importantly, consistency is noticeably worse : the power drops off more quickly.
Still, performance is much better than stock !


First test with the "long" barrel, 0.45 g pellet : nearly 500 fps !
5.08 joules, a gain of almost 50 fps, so it's working.

Chrony test : https://streamable.com/x6t3g3​

Second test with 0.51 g pellets : 464 fps, 5.10 joules

Chrony test : https://streamable.com/xulycu​

I extended the barrel on a Crosman MK1 and also saw a dramatic boost in fps. Haven’t fiddled with the valve yet

 

[Clark33]

Good stuff! I was wondering how to improve all that!
You’re an evil man, Clark …. you’ve armed me with the info I need to start yet another project .

Glad it helps ! Do you have the Glock ? Are you planning to do the same ?
Be careful with the valve or the magazine head. Spare parts for these models are not available, and it’s easy to mess things up completely.
Take a close look at the part beforehand to know where you can safely remove material without going through it.
But there’s quite a lot you can take off.

 

[Clark33]

I extended the barrel on a Crosman MK1 and also saw a dramatic boost in fps. Haven’t fiddled with the valve yet

Barrel extensions work really well on fixed-slide, non-blowback models, but that’s generally not the case with blowbacks like these.
If the slide starts opening and the CO2 is redirected backwards into the system before the projectile has exited the barrel,
it actually slows it down due to a suction effect. On the Umarex .43 versions, for example (which use the same blowback system as the .177 models), a longer barrel doesn’t increase power.

 

[Gerry52]

I didn't know 1/2gr pellets existed! Made from upseedaisium? . Lightest pellet I know of is 4.7gr, .177.

 

[borne2fly]

Glad it helps ! Do you have the Glock ? Are you planning to do the same ?
Be careful with the valve or the magazine head. Spare parts for these models are not available, and it’s easy to mess things up completely.
Take a close look at the part beforehand to know where you can safely remove material without going through it.
But there’s quite a lot you can take off.

No Glocks, but I have other pellet repeaters that could stand some refinement. All these lookalikes are made a bit rough, no doubt to keep them affordable, so I don’t mind replacing plastic and zamac parts that wear out with something made from steel.

 

[Clark33]

I didn't know 1/2gr pellets existed! Made from upseedaisium? . Lightest pellet I know of is 4.7gr, .177.

I actually wrote "g" everywhere, as in grams, not grains. Not sure where you saw grain mentioned
But yeah, 0.45 g is about 6.9 gr.

 

[Clark33]

New numbers on the PPQ with the 6 inches barrel and 0.51g pellets after adjusting barrel/pellet/valve for better alignement:


(fps) (Joules)
473 5.31 J
469.6 5.22 J
469 5.21 J
462.4 5.07 J
457.8 4.98 J
441.8 4.62 J
426.7 4.33 J
423.1 4.26 J


5.31 joules at peak !
The first shot were not filmed because I didn’t expect a gain.

Chrony test : https://streamable.com/co5xgd​